[rustyp]

Originally Posted by dewilson58

Actually they are infrastructure.

Also, landscape is part of infrastructure.

Landscape Architects design soft and hard infrastructures.
From LA site:
Landscape infrastructure is an evolutionary approach to strategizing economically and environmentally sustainable multipurpose infrastructure systems, reversing urban sprawl and regenerating our invaluable natural resources.

As the world faces an urgent need for new and repaired infrastructure systems, design and planning professionals have the crucial opportunity to reimagine networks that support multiple uses and functions. Multipurpose infrastructure conserves land, shares the financial load of its development, restores previously overlooked or damaged natural ecologies, reinforces healthy transit options, and provides public access to much needed open space.

Critical underlying infrastructure - high maintenance: